Fix Clang 13 -Wdeprecated-copy warnings

Clang 13 have new warning under the same group

include/boost/fusion/algorithm/transformation/pop_back.hpp

@@ -18,6 +18,11 @@
 #include <boost/mpl/int.hpp>
 #include <boost/mpl/if.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     template <typename Iterator_, bool IsLast>
@@ -168,5 +173,9 @@ namespace boost { namespace fusion
     }
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif